Blow-in-door actuation for after burner nozzle

ABSTRACT

The blow-in-doors for an exhaust nozzle are held in open position by an air piston located between adjacent doors that permits the doors to close when a predetermined pressure differential is built up on the doors. A cable and pulley connection from the air piston to the doors permits the doors to move independently with an actuating pressure still maintained on the doors.

United States Patent 1 [111 3,715,079 Thompson 5] Feb. 6, 1973 BLOW-IN-DOOR ACTUATION FOR [56] References Cited AFTER BURNER NOZZLE UNITED STATES PATENTS [75] Inventor: Charles L. Thompson, Vernon, 3,062,003 11/1962 Hamilton ..239/127.3 Conn. l 3 ,448,583 6/1969 Maguire "60/261 [73] Assignee: Uniti d Aircraft Corporation, East Primary Examiner s a m u 81 Feinble rg Hart Conn Attorney-Charles A. Warren [22] Filed: April 7, 1971 App]. No.: 131,971

U.S. Cl. .....239/265.l7, 239/1273, 239/265.37, 60/261, 60/262 Int. Cl. ..B63h 25/46 Field of Search ..239/127.3, 265.37; 60/261, 60/262 {57] ABSTRACT The blow-in-doors for an exhaust nozzle are held in open position by an air piston located between adjacent doors that permits the doors to close when a predetermined pressure differential is built up on the doors. A cable and pulley connection from the air piston to the doors permits the doors to move independently with an actuating pressure still maintained on the doors.

4 Claims, 5 Drawing Figures PATENTEDFEB' 6 I975 sum 2 or 2 NOE BLOW-IN-DOOR ACTUATION FOR AFTER BURNER NOZZLE SUMMARY OF THE INVENTION The copending application of Hasbrouck, et al., Ser. No. 131,972 filed Apr. 7, I971 having the same assignee as this application describes an arrangement for air actuation of the blow-indoors such that they are held in open position until a predetermined pressure differential develops on opposite sides of each door. The actuating piston is located between adjacent doors and is connected to both doors for moving them together into open position. The present invention is an improvement on that application in that it permits independent movement of the adjacent doors while maintaining the desired actuating pressure on both doors.

One feature of the invention is an air spring located between adjacent blow-in-doors and acting on both doors to apply substantially a constant opening pressure on each door throughout its travel with a connection to permit the doors to move relative to one another with the actuating pressure still maintained on both as a function of engine operation.

According to the invention, the blow-in-doors for the variable area nozzle are held in open position by an air spring device located between adjacent doors and connected to both to permit the blow-in-doors to close when the pressure differential across the doors reaches a predetermined amount. The connection from the doors to the air spring is a cable having a movable or rolling connection with the air spring device to permit the doors to move independently and still maintain the desired actuating pressure on both doors.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an external perspective view with parts broken away.

FIG. 2 is a longitudinal sectional view showing the nozzle construction.

FIG. 3 is a fragmentary sectional view similar to FIG. 2 but showing the construction between adjacent blowin-doors.

FIG. 4 is a transverse sectional view substantially along the line 4-4 of FIG. 2.

FIG. 5 is a longitudinal sectional view substantially along the line 55 of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT The invention is shown in connection with a turbofan engine which includes an outer duct 2, FIG. 1, within which is positioned a fan 4 at the front end of a compressor 6. The latter is positioned within the duct 2 and discharges through a diffuser 8, a burner 10, and a turbine 12. At the downstream end of the duct 2 is the nozzle construction 14 forming an extension of the duct 2.

Referring now to FIG. 2, the downstream end of the duct 2 terminates the afterburner duct 16 within which is positioned the afterburner liner 18. The primary nozzle 20 consisting of a plurality of flaps 22 surrounds and projects beyond the end of the afterburner duct. These flaps are pivotally mounted at their upstream ends to a movable actuating ring 24, the latter being moved axially through a plurality of actuating rods 26 connected 0 wardly and terminating in a ring 35 surrounding the duct 2 and attached thereto.

Attached to the supporting ring 35 are a plurality of struts 36, FIGS. 1 and 3, which extend in circumferentially spaced relation to one another from the ring 35 to a secondary support ring 38 on which the secondary nozzle flaps 40 are mounted. The function and actuation of the secondary flaps is not a part of the present invention and need not be described in detail. It is sufficient to note that the primary nozzle 20 forms a convergent variable area nozzle at the downstream end of the afterburner duct and the secondary nozzle flaps 40 form a convergent-divergent nozzle projecting downstream of the primary nozzle.

Between the two nozzles are positioned a plurality of blow-in-doors 42, FIGS. 1 and 2, located between the struts 36 and pivotally mounted at their upstream ends as best shown in FIG. 2. The purpose of these blow-indoors is well known. Such devices have been described previously as for example in the Hamilton US. Pat. No. 3,062,003. The present invention is concerned with the actuation of these doors.

As above stated, the blow-in-doors are individually supported for pivotal movement on supporting pins 44 carried by a support ring 46 attached to the ring 35. The blow-in-doors are caused to move inwardly for the admission of ambient air external of the duct 2 into the space between the primary and secondary nozzles under appropriate conditions of engine static and flight operations. 7

As best shown in FIGS. 2 and 4, each blow-in-door 42 has'adjacent each edge thereof a bracket 48 with an axial slot 50 therein. This bracket is spaced substantially from the pivot pin 44 as shown in FIG. 2. A lever 52, having a pin 54 at one end received in the slot 50, is secured at its opposite end to a shaft 54 located in a boss 56 in the strut 36 and also carrying an actuating link 58 located within the hollow strut 36.

Also positioned within the strut as shown in FIGS. 2, 3 and 4 is an air cylinder 60 supported to pivot on a transverse axis by a bolt 62. The cylinder has a piston 64 with a projecting piston rod 66, the latter ending in a yoke 68.

The yoke 68 has a pulley 70 thereon and a cable 71, connected at its ends to the free ends of adjacent arms 58, passes over said pulley. With the air piston exerting a pull to the right, FIG. 5, the cable is held tight and the arms 58 are pulled to swing the adjacent doors into open position. Should one door move at a different rate than the other, the cable will adjust to the different movements and will still keep the appropriate pressure on both arms 58. In this way the holding pressure on both doors is equal in whatever position the doors have with respect to one another. The cables and pulley constitute a flexible connecting means from the door actuating means to the piston, and a balancing means for maintaining an equal pull on each section of cable.

In order to provide a suitable pressure for actuating the blowcin-doors the conduit 72 is connected as best shown in FIG. 1 to the upstream or high pressure end of the compressor 6 there being a tap 74 provided at this point. In this way an adequate pressure is supplied so that the blow-in-doors are held in open position during those portions of the engine cycle where it is desirable to have air entering the openings provided by the blowin-doors.

lclaim:

1. An aircraft engine including a compressor, burner, turbine, and exhaust nozzle, said exhaust nozzle including a primary, variable-area nozzle having a support structure, a secondary variable-area nozzle downstream of said primary nozzle and having a secondary support structure, and blow-in-doors positioned axially between said two nozzles, in combination with means including a cylinder and piston positioned between adjacent blow-in-doors for moving said blowin-doors between closed and opened position, actuating means for said blow-in-doors, flexible connecting means from said actuating means to said piston, and balancing means between the flexible connecting means and said piston.

2. A device as in claim 1 in which the flexible connectlng means is a cable and the balancing means is a pulley on which the cable is mounted.

3. An exhaust nozzle for an aircraft engine including a primary, variable-area nozzle having a support structure, a secondary, variable-area nozzle downstream of said primary nozzle and having a secondary support structure and blow-in-doors positioned axially between said two nozzles, axially extending struts connecting the secondary support structure to the primary support structure with the blow-in-doors positioned between the struts, in combination with cylinder and piston means located in a strut for moving both of two adjacent blow-in-doors between closed and open position, linkage for moving each of said doors, and flexible means connecting said piston to said linkage including balancing means between said flexible means and said piston.

4. A nozzle as in claim 3 in which the flexible means is a cable extending between adjacent linkages and the balancing means is a pulley on which the cable is positioned. 

1. An aircraft engine including a compressor, burner, turbine, and exhaust nozzle, said exhaust nozzle including a primary, variable-area nozzle having a support structure, a secondary variable-area nozzle downstream of said primary nozzle and having a secondary support structure, and blow-in-doors positioned axially between said two nozzles, in combination with means including a cyLinder and piston positioned between adjacent blowin-doors for moving said blow-in-doors between closed and opened position, actuating means for said blow-in-doors, flexible connecting means from said actuating means to said piston, and balancing means between the flexible connecting means and said piston.
 1. An aircraft engine including a compressor, burner, turbine, and exhaust nozzle, said exhaust nozzle including a primary, variable-area nozzle having a support structure, a secondary variable-area nozzle downstream of said primary nozzle and having a secondary support structure, and blow-in-doors positioned axially between said two nozzles, in combination with means including a cyLinder and piston positioned between adjacent blow-in-doors for moving said blow-in-doors between closed and opened position, actuating means for said blow-in-doors, flexible connecting means from said actuating means to said piston, and balancing means between the flexible connecting means and said piston.
 2. A device as in claim 1 in which the flexible connecting means is a cable and the balancing means is a pulley on which the cable is mounted.
 3. An exhaust nozzle for an aircraft engine including a primary, variable-area nozzle having a support structure, a secondary, variable-area nozzle downstream of said primary nozzle and having a secondary support structure and blow-in-doors positioned axially between said two nozzles, axially extending struts connecting the secondary support structure to the primary support structure with the blow-in-doors positioned between the struts, in combination with cylinder and piston means located in a strut for moving both of two adjacent blow-in-doors between closed and open position, linkage for moving each of said doors, and flexible means connecting said piston to said linkage including balancing means between said flexible means and said piston. 